1 files changed, 17 insertions, 1 deletions
diff --git a/bot/converters.py b/bot/converters.py
index 4c41d0ece..4cfd663ba 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -2,6 +2,7 @@ import logging
 import re
 import typing as t
 from datetime import datetime
+from functools import partial
 from ssl import CertificateError
 
 import dateutil.parser
@@ -19,6 +20,7 @@ from bot.utils.regex import INVITE_RE
 log = logging.getLogger(__name__)
 
 DISCORD_EPOCH_DT = datetime.utcfromtimestamp(DISCORD_EPOCH / 1000)
+RE_USER_MENTION = re.compile(r"<@!?([0-9]+)>$")
 
 
 def allowed_strings(*values, preserve_case: bool = False) -> t.Callable[[str], str]:
@@ -481,7 +483,7 @@ class UserMentionOrID(UserConverter):
 
     async def convert(self, ctx: Context, argument: str) -> discord.User:
         """Convert the `arg` to a `discord.User`."""
-        match = self._get_id_match(argument) or re.match(r'<@!?([0-9]+)>$', argument)
+        match = self._get_id_match(argument) or RE_USER_MENTION.match(argument)
 
         if match is not None:
             return await super().convert(ctx, argument)
@@ -534,5 +536,19 @@ class FetchedUser(UserConverter):
             raise BadArgument(f"User `{arg}` does not exist")
 
 
+def _snowflake_from_regex(pattern: t.Pattern, arg: str) -> int:
+    """
+    Extract the snowflake from `arg` using a regex `pattern` and return it as an int.
+
+    The snowflake is expected to be within the first capture group in `pattern`.
+    """
+    match = pattern.match(arg)
+    if not match:
+        raise BadArgument(f"Mention {str!r} is invalid.")
+
+    return int(match.group(1))
+
+
 Expiry = t.Union[Duration, ISODateTime]
 FetchedMember = t.Union[discord.Member, FetchedUser]
+UserMention = partial(_snowflake_from_regex, RE_USER_MENTION)